Photosensitive read-out device for apertured records



Nov. 7,1967 ONE ET AL 3,351,765

PHOTOSENSITIVE READ- OUT DEVICE FOR APERTURED RECORDS 2 Sheets-Sheet 1Original Fil ed Jan. 4, 1965 5 mm W 7 W i H mm I v Z Q wk. J lm e 2 NWwE E I I r|l| rll.:. M

Nov. 7,1967 Y LO ETAL 3,351,765

PHOTOSENSITIVE READ-OUT DEVICE FOR APERTURED RECORDS Original Filed Jan.4, 1963 2 Sheets-Sheet 2 L'- s F-I I\ k I saw/ma I I i I I I I I q i J oo C; o o o o o z 5' d a 6 7 i United States Patent 3,351,765PHOTOSENSITIVE READ-OUT DEVICE FOR APERTURED RECORDS Robert L. Malone,Palos Verdes Peninsula, and George W. Floyd, Inglewood, Califl,assignors, by mesne assignments, to Ex-Cell-O Corporation, Detroit,Mich., a corporation of Michigan Continuation of application Ser. No.249,355, Jan. 4, 1963. This application Oct. 31, 1966, Ser. No. 595,2997 Claims. (Cl. 250-219) ABSTRACT OF THE DiSCLOSURE A read out device foruse in systems for reading information from record members such aspunched paper tape.

The read out device is constructed as a unitary assembly of aphotoelectric element mounted in a holder with a mask having non-roundapertures and a light transmitting member closing the assembly. Thenon-round aperture, which may be eye-shaped is defined to provide anelectrical output signal from the photoelectric element that is of agenerally square waveform.

This application is a continuation of the earlier filed applicationbearing Ser. No. 249,355, filed on Jan. 4, 1963, entitled, Read OutDevice, and assigned to the same assignee as the present application.

This invention relates to a read out device and more particularly toimprovements in the construction of a read out device for use withrecord members having light transmitting apertures.

At the present time information, and particularly 'digital information,is recorded on various recording media. One of the least expensive ofthese recording media involves the use of a record member whereininformation is represented in coded form by means of apertures or lighttransmitting areas. These record members commonly take the form of apunched card or a punched paper tape. These punched record members aresensed either mechanically or electrically, such as by means of sensingfingers or through the combination of a light source and a lightsensitive element respectively. The use of a light sensing element forreading punched paper tape allows very high reading speeds and has beenextensively adopted. The basic structure for reading a punched recordmember by means of a light sensitive cell is to utilize a light sourceon one side of the record member and a light sensitive element on theother side whereby an output indication is derived from the lightsensitive element only when light rays pass through the lighttransmitting aperture of the record member and impinge on the lightsensitive element. This type of operation, then, requires that therecord member proper have low light transmitting characteristics so asnot to activate the light sensitive element merely due to the lighttransmitted through the record member proper and thereby produceerroneous output signals or mask the signal derived or the signalsprovided by the light rays being transmitted through a recordedaperture.

At the present time commercially available photocell readers arearranged with a collimation block positioned between the light sourceand the light sensing element for collimating the light rays transmittedthrough a recorded aperture positioned within a particular area on therecord member and to direct the individual light rays to a correspondinglight sensitive element positioned immediately below the collimationplate to cause the light rays to impinge on the light element at anormal thereto. The use of such an arrangement required that thecollimation apertures in the block be precision drilled and also thatthe apertures be located precisely with regard to the active area of aphotocell to attempt to restrict the light rays from a particularaperture to impinge only on a light element individual to the apertureshaving the same physical location on the record member. Stateddifferently, the collimation apertures were generally round and thecenters of the collimation apertures had to be located to place them inaxial alignment with the centers of the active areas of the photocells.Furthermore, the light sensing element and the collimation block must bepositioned as close together as possible.

The use of such an arrangement has not been altogether satisfactory,particularly when the basic requirev ments of the output indicationsfrom the read out device are considered. To this end, the read outdevice should provide an output indication that has a wave shape that issubstantially square as a function of the motion of the record memberpast the sensing element. The output indication, which may be a currentsignal when a photo voltaic cell is employed, should be as large aspossible for a given amount of incident illumination. Furthermore, thelight rays should be so collimated that the effect of cross talk isminimized or the illumination of a cell is not dependent upon theillumination derived from an adjacent area on the record member butshould preferably be only a function of the normal incident illuminationand the individual cell sensitivity. The ability of the collimationapertures to transmit light rays is reduced as the length of the columnincreases and as the brightness of the column decreases. This would leadto the conclusion that a thin bright aperture is desirable from thestandpoint of the amplitude of the output signal derived from thephotocell but has been found to lead to cross talk. Such a collimationblock requires that it be structurally rigid whereby the thinness of theblock is limited. This ability to reject cross talk is also relateddirectly to the geometry of the bottom surf-aces of the record member orpaper tape with respect to the active area of the cells and anyintervening elements.

The present invention provides an improved read out device constructedas a unitary read out assembly adapted for reading punched recordmembers in the form of paper tape that solves the aforementionedproblems of the prior art and eliminates the physical and manufacturingdifficulties encountered in producing a record reader employing theseprior art teachings. The read out device is constructed to allow thelight sensitive element to be fully activated for approximately fiftypercent of the time interval a recorded aperture is passing over thelight sensitive element and produces a usable output indication in thegeneral form of a square output waveform even with record members thatare constructed of a material that is forty percent light transmitting.

From a structural standpoint, the read out assembly comprises a lightsensitive element, that may be a photovoltaic cell, for producingelectrical output indications in response to a light signal impingingthereon by means of a recorded light transmitting aperture on the recordmem her. The light cell is mounted in a holder to expose the lightactive area thereof and is mounted within a thin' mask having anon-round light transmitting aperture for exposing a preselected portionof the light exposed active area of the cell to provide an outputindication having a substantially square waveform and a preselectedamplitude. A light transmitting member is then mounted in the holderover the mask to function as a closure for the transmitting member ofthe read out device.

These and other features of the present invention may be more fullyappreciated when considered in the light of the following specificationand drawings, in which:

FIG. 1 is a side elevational view of a typical record reader embodyingthe invention;

FIG. 2 is a top plan view, with the light transmitting element omitted,of the read out device of the present invention showing the lightsensitive elements in dotted outline;

FIG. 3 is a front elevational view, with portions shown in section andin dotted outline, of the read out device;

FIG. 4 is a sectional view of the read out device taken along the line4-4 of FIG. 2;

FIG. 5 is a top plan View of the detached mask for the read out deviceof FIGS. 24;

FIG. 6 is an enlarged plan view of one of the nonround apertures of themask of FIG. 5; and

FIG. 7 is a top plan view of a pair of apertures arranged in a typicalside-by-side relationship on a record member and having the non-roundapertures superimposed thereon in cross-hatched fashion.

Now referring to FIG. 1 the general organization of a record reader andmore particularly a paper tape reader will be examined. The recordreader 10 includes a light source comprising a lamp 11 and spaced from acylindrical lens 12 for distributing the light onto the read out deviceproper. The lamp 11 may be constructed as a single filament lamp whereinthe filament comprises a thin wire extending longitudinally of the lampenvelope. The read out device is mounted in the top surface of a readout block 13 over which the record member is passed. The record memberis passed between the light source and more particularly the lens 12 andthe read out device 15. As illustrated in FIG. 1, the record member ismaintained in engagement with the read out device 15 by means of aretaining elment 14 which may be constructed as a spring clip mountedbetween the lens 12 and the block 13. As is well known, the passage ofthe record member over the read out device allows it to sense therecorded apertures to produce output indications corresponding to eachof the recorded apertures on the record member.

The read out device 15 is arranged to sense a conventional paper tapewherein the information is recorded in separate columns, for exampleeight information columns and a single timing channel wherein thesprocket holes are recorded.

The read out device 15 comprises a holder 16 for mounting a lightsensitive element 17 therein and a thin mask 18 is positioned within theholder 16 over the active area of the light sensitive element 17 alongwith a light transmitting element 19 positioned in engagement with themask 18 and further functioning as a closure for the holder 16 to form aunitary read out assembly. The mask 18 is provided with a non-roundaperture 18 for each information channel to be sensed to allow light tobe transmitted from the light source to the light sensitive element overa preselected area, as will be described in more detail hereinafter.

A light sensitive element that has been employed in the read out device15 is a photovoltaic cell that is commercially available from theHoffman Electronics Corporation of Los Angeles, Calif. and which cell isidenti fied as the Hoffman HPC-9-0l photovoltaic read out cell. Briefly,the read out cell is physically arranged as a single unit with aplurality of isolated sensing elements defined thereon, one for eachinformation channel on the record member and also one for the timingchannel. Therefore, when an eight column paper tape is employed as therecord member, the photovoltaic cell will have nine sensing elements,one for each information channel and one for the timing channel. Eachsensing element is arranged to receive the light transmitted from acorresponding tape channel and is further arranged with a common layerarranged below the separate sensing elements and which layer functionsas a common layer or electrode for all of the sensing elements includingthe timing channel sensing element. The electrical connection to thiscommon layer is shown in FIG. 4 by means of the lead wire 21 connectedthereto.

The light sensitive element or photovoltaic cell 17 is mounted in theholder 16 and which holder is constructed of a plastic and is providedwith an aperture or socket to accommodate the light sensitive elementwherein it is positioned with the light active areas of the individualsensing elements exposed to the light. The holder 16 is preferablyconstructed of a phenolic material and is further defined with a centralaperture 16 to allow the common lead wire 21 to be passed therethroughand includes a plurality of slots 16 angularly positioned on the holder16 to allow the lead wires for the other electrode for each sensingelement or the non-common electrodes for the sensing elements to bepassed therethrough. These non-common lead wires are arranged on theopposite side of the cell from the common layer thereof. As best seen inFIG. 4, the non-common lead wire for each sensing element is connectedto an electrical connector 22 which allows a heavy lead wire, such asthe non-common lead wire 23, to be simply pressed into the connector 22for making the necessary electrical connections to the read out device15.

The aperture mask 18 includes a non-round aperture 18* for eachinformation channel, 1-8, on the record memher and further includes around aperture 18', j, that corresponds to the location of the timingaperture on paper tape. The mask 18 is located in the holder 16 over thelight sensitive element 17 and in intimate engagement therewith. Theapertures provided for the mask 18 are positioned in alignment with theactive areas or individual sensing elements of the light sensitiveelement 17.

An important feature of the present invention is the construction of theaperture mask 18 and the particular configuration of the apertures toprovide a usable output indication in response to each recorded apertureon the record member. The construction of the aperture mask 18 and theapertures 18 is governed by the basic requirements for the outputindication from the light sensitive element 17. It is desired to have anoutput waveform from the element 17 that is substantially square andthat preferably has an amplitude that is as large as possible for agiven amount of incident illumination. The requirements of amplitude ofthe output signal and the square waveform requirement cannot both be metwith any practical aperture configuration and requires a compromisebetween these two characteristics. The apertures 18 are defined wherebythe amplitude of the output waveform is at a maximum for approximatelyfifty percent of the time that a recorded aperture is passing over itscorresponding light sensitive element. It should be evident that a verysmall round aperture would produce an output indication for a longerperiod than fifty percent but the very size of the aperture restrictsthe amount of light impinging on the light sensitive element andtherefore restricts the magnitude of the output signal that is'availablefrom the light sensitive element resulting in an output indication thatis not usable.

Referring to FIG. 7 in particular, it will be noted that a portion of apaper tape is illustrated wherein a pair of recorded apertures arrangedin the same information column are illustrated in a side-by-siderelationship. In a typical commercial application these adjacentrecorded apertures have their centers spaced on the order of 0.100 inchand the apertures have diameters on the order of 0.072 inch. Theconfiguration of the non-round aperture 18 has been defined to increasethe exposed active area of the light sensitive element that is exposedto the light over that exposed by a round aperture for example tothereby increase the amplitude of the output signal that is producedfrom the light sensitive element. Furthermore, the aperture 18 isfurther defined with regard to the total time interval that the apertureis presented to the individual area on the light sensitive element toproduce a usable signal over a preselected portion of the time interval.In this instance the apertures 18 are defined whereby the active areasof the individual light elements are fully exposed by means of theapertures for approximately fifty percent of the time interval that theaperture is passing over the cell.

The non-round apertures 18 as illustrated can be considered to be ofsemi-elliptical or eye-shaped configuration. The area of the aperture 18is defined by means of the common or overlapping area of two circleshaving the same diameter as the recorded apertures, 0.072 inch, andwhose centers are 0.050 inch apart; see FIG. 6. Accordingly, when suchan aperture 18 is positioned in relation to the paper tape as shown inFIG. 7, and the tape is passed from left to right, immediately after thetape moves to the right of the illustrated position the associated lightelement will not be fully activated and will be considered to be off andwill remain ofi until the succeeding recorded aperture is presented tothe same light element. Stated differently, when the recorded apertureis moved to the right of the line A as illustrated, the light cell isturned off and will remain off for a time interval corresponding to thetime required to travel the 0.050 inch between the lines A and B. Whenthe center line of the aperture 18* coincides with the line B, the cellwill be again fully activated and will remain so until it again ispositioned at a point corresponding to the line A. It will then be seenthat since the distance between the centers of adjacent recordedapertures is 0.100 inch, and the apertures are of the same diameter, theamount of time that the associated light cell is not fully activatedcorresponds to the dimension 0.050 inch, or one-half of 0.100 inch, thatthe cells will be fully activated for approximately fifty percent of thetime interval that the recorded aperture is passing over the lightelement. During this interval then the output response from the lightsensitive element will be substantially constant and will produce asquare topped output waveform which will decrease upon reaching a pointcorresponding to the line A and again increase to the desired amplitudeupon reaching a position corresponding to the line B and thereby providethe desired useful output signal corresponding to the recorded aperture.

It should be noted that when the non-round apertures 18 are of thedescribed semi-elliptical or eye-shaped configuration that the lightcell exposure is at a maximum and therefore provides a maximum celloutput signal for the above defined recorded aperture, aperture spacingon a fifty percent duty cycle. In addition, it has been found that thisaperture shape will also provide an output signal that has a waveformthat is more square than the output for any other aperture shape withinthe above defined parameters including maximum cell exposure.

The aperture plate 18 is constructed of a very thin metallic materialand preferably a material that allows the non-round apertures 18 to bereadily and accurately located therein. The material selected for themask 18 may depend upon the ability to chemically mill apertures of anon-round shape and which ability is a direct function of the type andthickness of material selected. It has been found that a metallic sheetof the copper alloy family having a thickness of approximately 0.002inch is satisfactory since the accuracy of the aperture positions andshapes are better than 0.001 inch when such a material is employed. Ithas further been found that when the thickness of the material increasesthe accuracy is reduced due to the tendency of the etching process tounder-cut the surface of the material. In one specific embodiment of theinvention the mask 18 was constructed of a beryllium copper having athickness of 0.005 inch.

It should now be appreciated that since a thin mask is employed that thegeometry of the mask 18 is such that the efiect of a column which isassociated with the collimation block no longer exists and, furthermore,the geometry of the mask 18 is such that it does not allow cross talk.In addition, the problems associated with aligning the collimationapertures and the light sensitive ele ment have been eliminated throughthe mounting of the aperture mask 18 and the light sensitive cell in oneblock. It will be appreciated, of course, that the location of thenon-round apertures 1 8a on the mask 18 and relative location to oneanother must be precisely controlled but is facilitated through theselection of a material in the copper alloy family that allows theseapertures to be chemically milled.

The construction of the read out device 15 is completed through theprovision of a light transmitting element 19 positioned over the mask 18and which light transmitting element functions as a closure for theaperture or socket of the holder 16. The light transmitting element 19may be in the form of a glass slide on the order of 0.013 inch that ispositioned in intimate engagement with the mask 18 and also has itsopposite surface arranged flush with the top surface of the holder 16,as illustrated in FIGS. 3 and 4. The light transmitting element 19 andthe aperture mask 18 are preferably held in position by means of epoxy.in the same fashion, the lead wire 21 is held in position by filling theaperture 16 with epoxy, and the connector 22 is similarly secured.

It should now be appreciated that the unitary assembly of the read outdevice 15 allows the record member or paper tape to ride or passdirectly over the assembly.

The read out device 15 of the present invention employing theaforementioned Hoffman photovoltaic cell has been defined to produce anoutput current of no less than microamperes at 0.2 volt from eachinformation channel and at the same voltage no less than 250microarnperes from the feed holes of a tape when the tape is illuminatedfrom a light source of milliwatts per square centimeter at a colortemperature of 2,800 degrees Kelvin.

It should be recognized that although the aperture 18 is illustrated asa round aperture for sensing the feed hole because of the differentcircuit requirements, it too may be defined as a non-round aperture 18*.

It should now be evident that one of the most important features of theinvention is the configuration of the apertures of the aperture mask. Tothis end, it will be recalled once again that the aperture is definedrelative to the production of a maximum output signal having asubstantially square waveform for a preselected duty cycle. Theimportance of the semi-elliptical or eye-shaped configuration can bebetter appreciated when a different duty cycle is considered wherein thelight sensitive element is activated for only forty per cent of the timeinterval a recorded aperture is passing over the light sensitiveelement. This same general aperture shape would be utilized for the samegeneral specifications for the record member except that now thedistance between the center of a pair of apertures recorded side-by-sideas in FIG. 7 and the lines A and B are 0.020 inch. With acenter-to-center spacing of these apertures of 0.100 inch, then thedistance between the lines A and B is now 0.060 inch rather than 0.050inch to provide a forty percent on time. The non-round aperture 18 isdefined in the same general fashion through the intersection of a pairof overlapping circles but to place the line A at the desired distancefrom the center of a recorded aperture.

What is claimed is:

1. A sensing element comprising a light sensitive member for producingelectrical output indications in response to a light signal impingingthereon, a holder having a socket for mounting the light sensitivemember to expose one side thereof to light, a mask having an eyeshapedlight transmitting aperture for exposing the corresponding light exposedportion of the light sensitive member and mounted in the holder socketover the light sensitive member, and a light transmitting member mountedin the holder over the mask to function as a closure for the socket tothereby define a unitary sensing assembly.

2. A read out device for sensing light transmitting apertures in arecord member and providing output indications thereof comprising alight sensitive member comprising a plurality of elements forindividually producing electrical output indications in response to alight signal impinging thereon, said elements each being arranged toreceive light from individual areas of a record member, a holder havingan aperture for mounting the light sensitive member to expose theindividual elements to light, a mask having individual lighttransmitting semielliptical apertures for exposing preselected portionsof the light exposed portions of corresponding light sensitive elementsand being mounted in the holder aperture over the light sensitivemember, said light transmitting apertures being defined to expose alight element a preselected portion of the time a recorded aperture ispassed over an element, and a light transmitting member mounted in theholder aperture over the mask to function as a closure for the holderaperture.

3. A read out device for sensing light transmitting apertures in arecord member and providing output indications thereof comprising aphotovoltaic cell comprising a plurality of individual elements forindividually producing electrical output indications in response to alight signal impinging on an element of said cell, said elements eachbeing arranged to receive light from individual areas of a recordmember, a holder having an aperture for mounting said cell to expose theindividual elements to light, a mask having individual semi-ellipticallight transmitting apertures for exposing preselected portions of thelight exposed portions of the corresponding elements and being mountedin the holder aperture with said cell, said light transmitting aperturesbeing defined to expose a light element a preselected portion of thetime a recorded aperture is passed over an element to cause theindividual elements to produce a substantially square output waveform ofa preselected amplitude as a function of the motion of the recordmember, and a relatively thin light transmitting member mounted in theholder aperture in contact with the mask and functioning as a closurefor the holder aperture to thereby define a unitary read out device.

4. A read out device for sensing recorded light transmitting aperturesin a record member and providing output indications thereof comprising alight sensitive element, a holder for mounting the light element withits ight active area exposed to the light, a metallic sheet having asemi-elliptical aperture mounted over the active element for exposing apreselected portion of the active area of the light element to allow thecell to be fully activated a preselected portion of the time a recordedlight transmitting aperture of a record member is positioned over thelight element, and a light trans-mitting member mounted over themetallic sheet and in engagement therewith and in the holder to functionas a closure for the holder aperture to thereby define a unitaryassembly whereby a record member to be read may be passed over the lighttransmitting member.

5. A readout device for sensing light transmitting apertures in a recordmember as defined in claim 4 wherein the metallic sheet is a berylliumcopper sheet and the light transmitting member comprises glass.

6. A read out device for sensing light transmitting apertures in arecord member as defined in claim 5 wherein the semi-elliptical apertureof the copper sheet is substantially eye-shaped to allow the lightelement to be fully exposed approximately fifty percent of the timeinterval a recorded light transmitting aperture is passed over the lightelement.

7. In a record reader having a light source comprising a single filamentlamp, a cylindrical lens, a record sensing element spaced from saidlens, said sensing element comprising a light sensitive membercomprising a plurality of individual light active elements forindividually producing electrical output indications in response to alight signal impinging on an element, said elements each being arrangedto receive light from individual areas of a record member positionedbetween said lens and said sensing element, a holder having an aperturefor mounting the light sensitive member to expose the individualelements to light, a mask having individual light transmittingsemi-elliptical apertures for exposing preselected portions of the lightexposed portions of corresponding light sensitive elements and beingmounted in the holder aperture over the light sensitive member, saidlight transmitting apertures being defined to expose a light element apreselected portion of the time a recorded aperture is passed over anelement, and a light transmitting member mounted in the holder apertureover the mask to form a unitary sensing assembly and allow a recordmember to be passed over the member.

References Cited UNITED STATES PATENTS 1,337,737 4/1920 Van der Bijl250-233 2,586,609 2/1952. Burke 250-219 X 2,939,016 5/1960 Cannon250-219 3,225,176 12/1965 Jones 250-219 3,268,735 8/1966 Beeh 250233WALTER STOLWEIN, Primary Examiner.

2. A READ OUT DEVICE FOR SENSING LIGHT TRANSMITTING APERTURES IN ARECORD MEMBER AND PROVIDING OUTPUT INDICATIONS THEREOF COMPRISING ALIGHT SENSITIVE MEMBER COMPRISING A PLURALITY OF ELEMENTS FORINDIVIDUALLY PRODUCING ELECTRICAL OUTPUT INDICATIONS IN RESPONSE TO ALIGHT SIGNAL IMPINGING THEREON, SAID ELEMENT EACH BEING ARRANGED TORECEIVE LIGHT FROM INDIVIDUAL AREAS OF A RECORD MEMBER, A HOLDER HAVINGAN APERTURE FOR MOUNTING THE LIGHT SENSITIVE MEMBER TO EXPOSE THEINDIVIDUAL ELEMENTS TO LIGHT, A MASK HAVING INDIVIDUAL LIGHTTRANSMITTING SEMI-